Package net.sf.saxon.functions

Class ScalarSystemFunction

java.lang.Object

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.ScalarSystemFunction

All Implemented Interfaces:

Callable, ArityOneFunction, IFunctionWithRetainedParameterNames, FunctionItem, GroundedValue, Item, Sequence

Direct Known Subclasses:

Abs, AccessorFn, Ceiling, DocumentUri_1, EncodeForUri, EscapeHtmlUri, Floor, GenerateId_1, IriToUri, LocalName_1, LowerCase, Name_1, NamespaceUriFn_1, NodeName_1, NormalizeSpace_1, Number_1, String_1, StringLength_1, UpperCase

public abstract class ScalarSystemFunction
extends SystemFunction
implements ArityOneFunction

A Scalar system function is a pure function that accepts a single item as its operand, returns a single atomic value as its result, typically returns an empty sequence if the argument is an empty sequence, and has no context dependencies.

Constructor Summary

Constructors

Constructor	Description
ScalarSystemFunction()

Method Summary

Modifier and Type	Method	Description
final Sequence	call(XPathContext context, Sequence[] arguments)	Evaluate the expression
Sequence	call1(XPathContext context, Sequence arg0)	Call a function with one argument
abstract AtomicValue	evaluate(Item arg, XPathContext context)	Abstract method that must be supplied in subclasses to perform the evaluation
Expression	makeFunctionCall(Expression[] arguments)	Make an expression that either calls this function, or that is equivalent to a call on this function
Sequence	resultWhenEmpty()	Method that may be supplied in subclasses, to indicate the result that is returned when an empty sequence is supplied as the argument value.

Methods inherited from class net.sf.saxon.functions.SystemFunction

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getElaborator, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getNetCost, getOperandRoles, getParameterNames, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, getUniqueIdentifier, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunction40, makeOptimizedFunctionCall, makeTrueFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, toShortString, toString, typeCheckCaller

Methods inherited from class net.sf.saxon.functions.AbstractFunction

atomize, deepEqual40, deepEquals, effectiveBooleanValue, getAnnotations, getUnicodeStringValue, isArray, isMap, makeNewContext, simplify, typeCheck

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.sf.saxon.om.FunctionItem

getGenre

Methods inherited from interface net.sf.saxon.om.GroundedValue

asIterable, concatenate, containsNode, materialize

Methods inherited from interface net.sf.saxon.om.Item

getLabel, getLength, getStringValue, head, isStreamed, itemAt, iterate, reduce, subsequence

Methods inherited from interface net.sf.saxon.om.Sequence

makeRepeatable

Constructor Details

ScalarSystemFunction

public ScalarSystemFunction()

Method Details

call1

public Sequence call1(XPathContext context,
 Sequence arg0)
               throws XPathException

Call a function with one argument

Specified by:

call1 in interface ArityOneFunction

Parameters:

context - the dynamic evaluation context

arg0 - the first argument

Returns:

the result of the function call

Throws:

XPathException - if the call fails with a dynamic error

evaluate

public abstract AtomicValue evaluate(Item arg,
 XPathContext context)
                              throws XPathException

Abstract method that must be supplied in subclasses to perform the evaluation

Parameters:

arg - the supplied argument

context - the dynamic context

Returns:

the result of the evaluation. May be null indicating the result is an empty sequence.

Throws:

XPathException - if a dynamic error occurs

resultWhenEmpty

public Sequence resultWhenEmpty()

Method that may be supplied in subclasses, to indicate the result that is returned when an empty sequence is supplied as the argument value. The default is to return the empty sequence

Returns:

the result of evaluation when the supplied argument is an empty sequence

call

public final Sequence call(XPathContext context,
 Sequence[] arguments)
                    throws XPathException

Evaluate the expression

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences

Returns:

the result of the evaluation, in the form of a Sequence

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression

makeFunctionCall

public Expression makeFunctionCall(Expression[] arguments)

Description copied from class: SystemFunction

Make an expression that either calls this function, or that is equivalent to a call on this function

Overrides:

makeFunctionCall in class SystemFunction

Parameters:

arguments - the supplied arguments to the function call

Returns:

either a function call on this function, or an expression that delivers the same result